Problem: What is the least common multiple of $4$ and $10$ ? $\text{lcm}(4, 10) = $
Answer: The least common multiple is the smallest number that is a multiple of $4$ and $10$. We know that $4 \times 10$ (or $40$ ) is a common multiple, but is it the least common multiple? Write out the multiples of $10$ until we find a number divisible by $4$. $10, 20$ So, the least common multiple of $4$ and $10$ is $20$.